Substrate processing apparatus and substrate processing method

ABSTRACT

An apparatus for processing reaction products that are deposited when an etching target film contained in a target object to be processed is etched is provided with: a processing chamber; a partition plate; a plasma source; a mounting table; a first processing gas supply unit; a second processing gas supply unit. The processing chamber defines a space, and the partition plate is arranged within the processing chamber and divides the space into a plasma generating space and a substrate processing space, while suppressing permeation of ions and vacuum ultraviolet rays. The plasma source generates a plasma in the plasma forming space. The mounting table is arranged in the substrate processing space to mount the target object thereon.

FIELD OF THE INVENTION

The present invention relates to a substrate processing apparatus and asubstrate processing method.

BACKGROUND OF THE INVENTION

Patent Document 1 discloses a substrate processing method formanufacturing a MRAM (Magnetic Random Access Memory) device byprocessing a multi-layered object including a Magnetic Tunnel Junction(MTJ) having a lower magnetic layer, an upper magnetic layer and aninsulation layer interposed therebetween. More specifically, the MRAMdevice is manufactured by (a) forming a first mask on an upper electrodelayer, (b) plasma-etching the upper electrode layer, the upper magneticlayer and the insulation layer, (c) removing the first mask andconductive reaction products which are generated in the etching and aredeposited on a side wall and the like, (d) forming a second mask on theupper electrode layer, (e) etching a lower electrode layer, and (f)removing the second mask and conductive reaction products which aregenerated in the etching and are deposited on the side wall and thelike. In this method, a gas including fluorine containing gas, and H₂Ovapor or NH₃ is used as a gas for removing the conductive by-products.The gas may be excited by a plasma.

-   Patent Document 1: U.S. Patent Application Publication No.    2004-0137749

However, when forming a device by etching a layer containing metal, suchas a MRAM device or the like, since surfaces of the metal-containinglayer is exposed by the etching, the exposed portion may be likely to beoxidized. Therefore, the metal-containing layer needs to be protected bycovering the layer with a protection layer made of an insulator. Inaddition, before covering the layer with the protection layer, it isnecessary to remove a reaction product which is produced in the etchingand deposited on a side wall and the like by using the method disclosedin Patent Document 1.

The reaction product may contain not only metal but also metal oxide,metal halide or the like. However, in the substrate processing methoddescribed in Patent Document 1, a gas as it is reacts with theconductive reaction product or a gas excited by a plasma reacts with theconductive reaction product, so that the reaction product may not beremoved properly. Therefore, in the related art, there is a need toprovide a substrate processing apparatus and a substrate processingmethod which are capable of properly removing reaction productsgenerated when an etching target film is etched.

SUMMARY OF THE INVENTION

In accordance with an aspect of the present invention, there is provideda substrate processing apparatus for treating reaction productsdeposited in etching an etching target layer included in a targetobject.

The substrate processing apparatus including: a processing chamberdefining a space; a partition plate which is disposed in the processingchamber and partitions the space into a plasma generating space and asubstrate processing space, the partition plate being configured tosuppress transmission of ions and vacuum ultraviolet rays; a plasmasource configured to generate a plasma in the plasma generating space;and a mounting table disposed in the substrate processing space formounting the target object thereon. The substrate processing apparatusfurther includes: a first processing gas supply unit configured tosupply a first processing gas into the plasma generating space, thefirst processing gas to be dissociated by the plasma to generateradicals; and a second processing gas supply unit configured to supply asecond processing gas into the substrate processing space, the secondprocessing gas reacting with the reaction products without being exposedto the plasma.

In the substrate processing apparatus, the partition plate is disposedin the processing chamber whose space is partitioned into the plasmagenerating space and the substrate processing space by the partitionplate. The partition plate transmits neural radicals while suppressingtransmission of ions and vacuum ultraviolet rays. In addition, the firstprocessing gas supply unit supplies the first processing gas into theplasma generating space. With this configuration, ions generated fromthe first processing gas are blocked by the partition plate and onlyradicals generated from the first processing gas are moved into thesubstrate processing space and react with the reaction products.

In addition, the second processing gas supply unit supplies the secondprocessing gas into the substrate processing space. The secondprocessing gas reacts with the reaction products without being exposedto the plasma. Thus, owing to interaction between the radicals and thesecond reactant processing gas, it is possible to properly remove thereaction products generated when the etching target layer is etched.

The substrate processing apparatus may further include a gas exhaustunit which is provided to the substrate processing space anddepressurizes the space of the processing chamber.

With this configuration, the radicals generated from the firstprocessing gas can be properly moved into the substrate processingspace. In addition, for example, when a reaction product is generated byreaction between the second processing gas and the reaction products,the generated reaction product can be exhausted without being decomposedby a plasma.

The partition plate may include at least two plate-shaped membersarranged to overlap with each other from the plasma generating spacetoward the substrate processing space. Each plate-shaped member may havea plurality of through-holes penetrating therethrough in the overlappingdirection. The through-holes of one of the at least two plate-shapedmembers preferably do not overlap with the through-holes of the otherones of the at least two plate-shaped members in the overlappingdirection.

With this configuration, the radicals generated from the firstprocessing gas can be moved into the substrate processing space whileblocking ions and ultraviolet rays generated from the first processinggas by the partition plate.

The radicals may cause a reduction reaction, an oxidation reaction, achloride reaction or a fluoride reaction. The first processing gas maycontain hydrogen atoms, oxygen atoms, chlorine atoms or fluorine atoms.

From the reaction between these radicals and the reaction products, thereaction products can be changed into a substance which is easily reactwith the second processing gas.

The second processing gas may include a gas whose reaction with thereaction products is affected by a temperature of the mounting table.The second processing gas may include an electron-donating gas.

Thus, by supplying the second reactant processing gas into the substrateprocessing space not exposed to the plasma, the second processing gascan react with the reaction products without being dissociated.

In accordance with another aspect of the present invention, there isprovided a substrate processing method for treating reaction productsdeposited in etching an etching target layer included in a target objectby using a substrate processing apparatus.

The substrate processing apparatus includes a processing chamberdefining a space; a partition plate which is disposed in the processingchamber and partitions the space into a plasma generating space and asubstrate processing space, the partition plate being configured tosuppress transmission of ions and vacuum ultraviolet rays; a plasmasource configured to generate a plasma in the plasma generating space;and a mounting table disposed in the substrate processing space formounting the target object thereon.

The substrate processing apparatus further includes a first processinggas supply unit configured to supply a first processing gas into theplasma generating space, the first processing gas to be dissociated bythe plasma to generate radicals; and a second processing gas supply unitconfigured to supply a second processing gas into the substrateprocessing space, the second processing gas reacting with the reactionproducts without being exposed to the plasma.

The substrate processing method includes: a first step of generating theradicals by supplying the first processing gas from the first processinggas supply unit into the plasma generating space in which a plasma isgenerated, and moving the generated radicals into the substrateprocessing space to cause a reaction with the reaction products; and asecond step of supplying the second processing gas from the secondprocessing gas supply unit into the substrate processing space to causea reaction with the reaction products.

In the substrate processing apparatus used in this method, the partitionplate is disposed in the processing chamber whose space is partitionedinto the plasma generating space and the substrate processing space bythe partition plate. The partition plate transmits neural radicals whilesuppressing transmission of ions and vacuum ultraviolet rays. Inaddition, the first processing gas supply unit supplies the firstprocessing gas into the plasma generating space. By performing the firststep using the apparatus configured as above, ions generated from thefirst processing gas are blocked by the partition plate and onlyradicals generated from the first processing gas can be moved into thesubstrate processing space and react with the reaction products.

In addition, in the substrate processing apparatus executing thismethod, the second processing gas supply unit supplies the secondprocessing gas into the substrate processing space. By performing thesecond step using the apparatus configured as above, the secondprocessing gas can react with the reaction products without beingexposed to plasma. Thus, owing to interaction between the radicals andthe second reactant processing gas, it is possible to properly removethe reaction products generated when the etching target layer is etched.

The first step and the second step may be performed in the samesubstrate processing apparatus.

Thus, since reactions of the radicals and the second processing gas canbe consistently performed in vacuum, it is possible to prevent newreaction products from being formed by processing.

The first step may be performed before or at the same time of the secondstep.

With this configuration, radicals can react with the reaction productsso that the reaction products can be changed into a substance which iseasily react with the second processing gas.

The etching target layer may include a metal-containing layer.

With this, even when the reaction products are so-called hardly-etchedsubstances containing metal, metal oxide, metal halogen compounds or thelike, it is possible to properly remove reaction products generated whenthe etching target layer is etched by interaction between the radicalsand the second reactant processing gas.

Effect of the Invention

In accordance with the aspects of the present invention, it is possibleto properly remove reaction products generated when an etching targetlayer is etched.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view schematically showing one example of a MRAM devicemanufactured by a substrate processing method in accordance with oneembodiment.

FIG. 2 is a schematic view of a substrate processing system including asubstrate processing apparatus in accordance with one embodiment.

FIG. 3 is a flowchart showing the substrate processing method inaccordance with the embodiment.

FIGS. 4 to 9 are views for presenting a process of manufacturing theMRAM device shown in FIG. 3.

FIG. 10 is a schematic view of a substrate processing apparatus inaccordance with one embodiment.

FIG. 11 is a plan view of a high frequency antenna shown in FIG. 10.

FIG. 12 is a schematic view for explaining second gas supply nozzles andthe partition plate shown in FIG. 10.

FIG. 13 is a flowchart for explaining details of a reaction productremoving process.

FIGS. 14A and 14B are schematic views of cross-sectional SEM images of atarget object obtained in a comparative example.

FIGS. 15A to 15C are schematic views of cross-sectional SEM images of atarget object obtained in a first test example.

FIGS. 16A and 16B are schematic views of SEM images of the target objectobtained in the first test example.

FIGS. 17A to 17C are schematic views of cross-sectional SEM images of atarget object obtained in a second test example.

FIGS. 18A and 18B are schematic views of SEM images of the target objectobtained in the second test example.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments of the present invention will be described indetail with reference to the accompanying drawings. Throughout thedrawings, the like parts are denoted by like reference numerals.

FIG. 1 is a cross sectional view of a MRAM device 100 manufactured by asubstrate processing method in accordance with an embodiment. Referringto FIG. 1, the MRAM device 100 is formed on a substrate B and includes alower electrode 101, a pinning layer 102, a second magnetic layer 103,an insulation layer 104, a first magnetic layer 105, an upper electrodelayer 106 and an etching mask 107, which are laminated in that orderfrom the bottom. In addition, an insulation film 108 is formed on sidewalls of the first magnetic layer 105, the upper electrode layer 106 andthe etching mask 107 of the MRAM device 100.

The lower electrode layer 101 is a conductive electrode member formed onthe substrate B. The thickness of the lower electrode layer 101 is,e.g., about 5 nm. The pinning layer 102 is interposed between the lowerelectrode layer 101 and the second magnetic layer 103. The pinning layer102 fixes a magnetization direction of the lower magnetic layer 101 bythe pinning effect of an antiferromagnetic body. The pinning layer 102is formed of an antiferromagnetic material such as, e.g., iridiummanganese (IrMn), platinum manganese (PtMn) or the like and itsthickness is, e.g., about 7 nm.

The second magnetic layer 103 includes a ferromagnetic material layerformed on the pinning layer 102. The second magnetic layer 103 acts as aso-called pinned layer whose magnetization direction remains constant bythe pinning effect of the pinning layer 102 without being affected by anexternal magnetic field. The second magnetic layer 103 is formed of,e.g., CoFeB and its thickness is, e.g., about 2.5 nm.

The insulation layer 104 is interposed between the second magnetic layer103 and the first magnetic layer 105. The interposition of theinsulation layer 104 between the second magnetic layer 103 and the firstmagnetic layer 105 causes a tunnel magnetoresistance effect between thesecond magnetic layer 103 and the first magnetic layer 105. That is,electric resistance corresponding to the relationship (parallelism orantiparallelism) between the magnetization direction of the secondmagnetic layer 103 and the magnetization direction of the first magneticlayer 105 is generated between the second magnetic layer 103 and thefirst magnetic layer 105. The insulation layer 104 is formed of Al₂O₃ orMgO and its thickness is, e.g., 1.3 nm.

The first magnetic layer 105 includes a ferromagnetic layer formed onthe insulation layer 104. The first magnetic layer 105 acts as aso-called free layer whose magnetization direction follows an externalmagnetic field which is magnetic information. The first magnetic layer105 is formed of CoFeB and its thickness is, e.g., about 2.5 nm.

The upper electrode layer 106 is a conductive electrode member formed onthe first magnetic layer 105. The thickness of the upper electrode layer106 is, e.g., about 5 nm. The etching mask 107 is formed on the upperelectrode layer 106. The etching mask 107 is shaped to correspond to aplanar shape of the MRAM device 100. The etching mask 107 is formed of,e.g., Ta, TiN, Si, W, Ti or the like and its thickness is, e.g., 50 nm.

Next, a method for manufacturing the MRAM device 100 will be described.The MRAM device 100 is manufactured by, e.g., a substrate processingsystem shown in FIG. 2. FIG. 2 is a plan view schematically showing asubstrate processing system in accordance with an embodiment. Thesubstrate processing system 20 shown in FIG. 2 includes substrate stages22 a to 22 d, containers 24 a to 24 d, a loader module LM, load-lockchambers LL1 and LL2, process modules PM1 to PM3 and a transfer chamber21.

The substrate stages 22 a to 22 d are arranged along one side of theloader module LM. The containers 24 a to 24 d are mounted on thesubstrate stages 22 a and 22 d, respectively. Target objects W to beprocessed are accommodated in the containers 24 a to 24 d.

A transfer robot Rb1 is provided within the loader module LM. Thetransfer robot Rb1 takes out a target object W accommodated in one ofthe containers 24 a to 24 d and transfers it to the load-lock chamberLL1 or LL2.

The load-lock chambers LL1 and LL2 are arranged along another side ofthe loader module LM and serves as a preliminary vacuum chamber. Theload-lock chambers LL1 and LL2 are connected to the transfer chamber 21through respective gate valves.

The transfer chamber 21 is a chamber of which inner space can bedepressurized and a transfer robot Rb2 is provided therein. The transferchamber 21 is connected with the process modules PM1 to PM3 throughrespective gate valves. The transfer robot Rb2 takes the target object Wout of the load-lock chamber LL1 or LL2 and transfers it to the processmodules PM1, PM2 and PM3 sequentially. The process modules PM1, PM2 andPM3 of the substrate processing system 20 may be a substrate processingapparatus (a substrate processing apparatus for removing reactionproducts), a film forming apparatus and a plasma etching apparatus inaccordance with the embodiment, respectively. The film forming apparatusmay be a CVD (Chemical Vapor Deposition) apparatus. In the followingdescription, for the sake of easy understandings of description, e.g.,the process module PM1 is employed for a substrate processing apparatusfor removing reaction products, the process module PM2 is employed for afilm forming apparatus, and the process module PM3 is employed for aplasma etching apparatus.

The MRAM device 100 is manufactured according to, e.g., a flowchartshown in FIG. 3. FIG. 3 is a flowchart showing a substrate processingmethod in accordance with the embodiment. In the substrate processingmethod in accordance with the embodiment, as shown in FIG. 3, amulti-layered target object W is manufactured by the process module PM2as the film forming apparatus at step S1. Next, the target object W ismounted on an electrostatic chuck in the process module PM3 as theplasma etching apparatus. FIG. 4 shows one example of the target objectW manufactured in an intermediate step of the method for manufacturingthe MRAM device 100. The target object W is a multi-layered materialincluding the lower electrode layer 101, the pinning layer 102, thesecond magnetic layer 103, the insulation layer 104, the first magneticlayer 105 and the upper electrode layer 106 which are laminated on thesubstrate B. An etching mask 107 having a predetermined planar shape isdisposed on the upper electrode layer 106.

Hereinafter, a substrate processing method in accordance with theembodiment will be described by way of an example of the target object Wshown in FIG. 4.

At step S2, the upper electrode layer 106 is etched first. An etchinggas used at this time is optional. For example, the etching gas may beCl₂, CH₄, He, N₂, Ar or the like. For example, a processing gascontaining chlorine (Cl₂) is supplied and a plasma is generated to etchthe target object W. The processing gas may include an inert gas such asHe, N₂, Ar or the like, and H₂. A kind of gas to achieve sufficientselectivity of the first magnetic layer 105 and the insulation layer 104is employed as the processing gas. In step S2, a region of the firstmagnetic layer 105, which is not covered by the etching mask 107, reactswith and is etched by a first processing gas, but the insulation layer104 is not etched. Thus, in step S2, the etching is completed at asurface of the insulation layer 104.

In step S2, when the first magnetic layer 105 is etched using theprocessing gas, a material to be etched reacts with the processing gasand a reaction product is generated. The reaction product may includemetal which is contained in the mask 107 and the first magnetic layer105, oxide, chloride, nitride or halide of the metal, a C orSi-containing compound or the like. The reaction product is adhered, asa residue Z, to side walls of the first magnetic layer 105, the upperelectrode layer 106 and the etching mask 107, as shown in FIG. 5. Theresidue Z may cause a leak current in the MRAM because it contains aconductive substance.

At step S3, in order to remove the residue Z, the target object W istransferred to the process module PM1 as the substrate processingapparatus in accordance with the embodiment. Step S3 will be describedin detail later. After the residue Z is removed from the side walls ofthe first magnetic layer 105, the upper electrode layer 106 and theetching mask 107 as shown in FIG. 6, the process proceeds to step S4.

In the substrate processing method in accordance with the embodiment, atstep S4, the target object W is transferred to the process module PM2 asthe film forming apparatus (e.g., CVD apparatus) in which the surface ofthe target object W is coated with the insulation film 108 as shown inFIG. 7. The insulation film 108 is formed of, e.g., SiN or SiO₂.Thereafter, the target object W is returned to the process module PM3 asa plasma etching apparatus in which the insulation film 108 is etchedsuch that the insulation film 108 is left at the side walls of the firstmagnetic layer 105, the upper electrode layer 106 and the etching mask107.

In the substrate processing method in accordance with the embodiment, atstep S5, a processing gas such as a methane (CH₄)-containing gas issupplied to generate a plasma to etch the insulation layer 104, thesecond magnetic layer 103, and the pinning layer 102. The target objectW etched in step S5 is shown in FIG. 8. The processing gas may includean inert gas such as He, N₂, Ar or the like, a carbonyl group-containinggas, H₂ and the like, in addition to the methane gas. In step S5,regions of the insulation layer 104, the second magnetic layer 103 andthe pinning layer 102, which are not covered by the etching mask 107 andthe insulation film 108, are etched. Thus, the pinning layer 102, thesecond magnetic layer 103 and the insulation layer 104 are formed to bewider than the width of the first magnetic layer 105, the upperelectrode layer 106 and the etching mask 107 by the width of theinsulation film 108 formed at the side walls of the first magnetic layer105, the upper electrode layer 106 and the etching mask 107.

In the substrate processing method in accordance with the embodiment, atstep S6, a processing gas is supplied to generate a plasma to etch thelower electrode layer 101. The target object W etched in step S6 isshown in FIG. 9. The processing gas may include an inert gas such as He,N₂, Ar or the like, a carbonyl group-containing gas, CH₄, H₂ and thelike. In step S6, a region of the lower electrode layer 101, which isnot covered by the etching mask 107 and the insulation film 108, isetched. Thus, the lower electrode 101 is formed to be wider than thewidth of the first magnetic layer 105, the upper electrode layer 106 andthe etching mask 107 by the width of the insulation film 108 formed atthe side walls of the first magnetic layer 105, the upper electrodelayer 106 and the etching mask 107.

When step S6 is completed, the plasma processing shown in FIG. 3 iscompleted. Thus, a MRAM device having a desired shape is formed from thetarget object W having a multi-layer structure.

Next, a substrate processing apparatus used to remove reaction productsin step S3 will be described. Here, an inductively coupled plasmaprocessing apparatus is illustrated for plasma-processing a targetobject W (e.g., a semiconductor wafer (hereinafter, abbreviated as a“wafer”)). The wafer W is processed by using a plasma of a processinggas excited in a processing chamber by applying an RF (Radio Frequency)power to a planar high frequency antenna. FIG. 10 is a schematic viewshowing a plasma processing apparatus 10 which can be used as theprocess module PM1 shown in FIG. 2, in accordance with the embodiment.FIG. 11 is a plan view of a high frequency antenna 140 shown in FIG. 10when viewed from the top.

The plasma processing apparatus 10 includes e.g., cylindrical processingchamber 192 formed of a metal (e.g., aluminum). The processing chamber192 has a space in its inside. The processing chamber 192 is not limitedto the cylindrical shape. For example, the processing chamber 192 mayhave a square column shape (e.g., a box shape).

A mounting table 110 for mounting a wafer W is provided on the bottom ofthe processing chamber 192. The mounting table 110 has a columnar shape(e.g., a cylindrical columnar shape) and is formed of aluminum or thelike. The mounting table 110 is not limited to the cylindrical shape.For example, the mounting table 110 may have a square columnar shape(e.g., polygonal columnar shape). Although not shown, the mounting table110 may include an electrostatic chuck for attracting and holding thewafer W by a Coulomb force, a temperature adjustment mechanism such as aheater and a coolant passage, and the like to provide various functions,as necessary. Modifications of the mounting table 110 will be describedin detail later.

A plate-shaped dielectric body 194 formed of, e.g., quartz glass,ceramics or the like is provided at a ceiling of the processing chamber192 to face the mounting table 110. In detail, the plate-shapeddielectric body 194 has a circular plate shape and is air-tightlyattached to the ceiling of the processing chamber 192 so that it closesan opening formed at the ceiling.

A partition plate 230 for partitioning a space into a plasma generatingspace S1 and a substrate processing space S2 is provided inside theprocessing chamber 192. The plasma generating space S1 is a space wherea plasma is generated by a plasma source. The substrate processing spaceS2 is a space in which the wafer W is mounted. The partition plate 230includes at least two plate-shaped members 230A and 230C. The twoplate-shaped members 230A and 230C are arranged to overlap with eachother from the plasma generating space S1 to the substrate processingspace S2. A spacer 230B is interposed between the plate-shaped member230A and the plate-shaped member 230C for maintaining a gap between theplate-shaped member 230A and the plate-shaped member 230C at apredetermined value.

FIG. 12 is a schematic view of the partition plate 230. As shown in FIG.12, the plate-shaped members 230A and 230C respectively includes aplurality of slits 231A and a plurality of slits 231C penetratingtherethrough in the overlapping direction. These slits arethrough-holes. Slits 231A in the plate-shaped member 230A are arrangednot to overlap with slits 231C in the plate-shaped member 230C whenviewed from the overlapping direction. The plate-shaped members 230A and230C are made of, e.g., quartz glass. The spacer 230B is made of, e.g.,Al. The partition plate 230 for partitioning the plasma generating spaceS1 and the substrate processing space S2 functions as a so-called iontrap for suppressing transmission of ions and vacuum ultraviolet ray.

A first gas supply unit 120A for supplying a first processing gas isconnected to the processing chamber 192. The first gas supply unit 120Asupplies the first processing gas into the plasma generating space S1. Agas inlet 121 is provided in a side wall of the processing chamber 192and a gas supply source 122A is connected to the gas inlet 121 through agas supply line 123A. A flow rate controller (e.g., a mass flowcontroller) 124A for controlling a flow rate of the first processing gasand an on-off valve 126A are disposed in the midway of the gas supplyline 123A. With the gas supply unit 120A, the first processing gas fromthe gas supply source 122A is controlled to have a specific flow rate bythe mass flow controller 124A and is supplied into the plasma generatingspace S1 of the processing chamber 192 through the gas inlet 121.

The first processing gas is decomposable and, thus, it is dissociated togenerate radicals by a plasma generated by the plasma source. Theradicals may cause reduction reaction, oxidation reaction, chloridereaction or fluoride reaction. The first processing gas may be a gascontaining hydrogen atoms, oxygen atoms, chlorine atoms or fluorineatoms. Specifically, the first processing gas may be Ar, N₂, O₂, H₂, He,BCl₃, Cl₂, CF₄, NF₃, CH₄ or SF₆. The first processing gas whichgenerates radicals for reduction reaction may be H₂ or the like. Thefirst processing gas which generates radicals for oxidation reaction maybe O₂ or the like. The first processing gas which generates radicals forchloride reaction may be BCl₃, Cl₂ or the like. The first processing gaswhich generates radicals of fluoride reaction may be CF₄, NF₃, SF₆ orthe like.

A second gas supply unit 120B for supplying a second processing gas orthe like is connected to the processing chamber 192. The second gassupply unit 120B supplies the second processing gas into the substrateprocessing space S2. A gas supply head 240 is disposed in the substrateprocessing space S2 of the processing chamber 192 and a gas supplysource 122B is connected to the gas supply head 240 through a gas supplyline 123B. FIG. 12 shows the gas supply head 240 disposed below thepartition plate 230. The gas supply head 240 includes a plurality of gasholes 240A opened downward (i.e., toward the mounting table 110). Inthis manner, as the gas flows downward, the second reactant processinggas can be appropriately supplied onto the wafer W. The gas holes 240Amay be opened upward (i.e., toward the partition plate 230). In thiscase, radicals transmitting through the partition plate 230 can beappropriately mixed with the second processing gas. A flow ratecontroller (e.g., a mass flow controller (MFC)) 124B for controlling aflow rate of the second processing gas and an on-off valve 126B aredisposed in the midway of the gas supply line 123B. With this gas supplyunit 120B, the second processing gas from the gas supply source 122B iscontrolled to have a specific flow rate by the mass flow controller 124Band is supplied into the substrate processing space S2 of the processingchamber 192 through the gas supply head 240.

The second processing gas is a reactant gas which reacts with a reactionproduct without being exposed to a plasma. The second processing gas mayinclude a gas whose reaction with the reaction product is affected by atemperature of the mounting table 110, such as HF, Cl₂, HCl, H₂O, PF₃,F₂, ClF₃, COF₂, cyclopentadiene, amidinate or the like. The secondprocessing gas may also include an electron-donating gas. Theelectron-donating gas refers generally to a gas composed of atoms havinga large difference in terms of electronegativity or ionization potentialor a gas composed of atoms having unshared electron pairs. Theelectron-donating gas has a property of easily donating electrons toother compounds. For example, the electron-donating gas has a propertyof bonding as a ligand with a metal compound. The electron-donating gasmay include SF₆, PH₃, PF₃, PCl₃, PBr₃, Pl₃, CF₄, AsH₃, SbH₃, SO₃, SO₂,H₂S, SeH₂, TeH₂, Cl₃F, H₂O, H₂O₂, a carbonyl group-containing gas or thelike.

Although it is shown in FIG. 10 that the gas supply units 120A and 120Bare presented by a gas line of a single system for the purpose ofsimplification of description, the gas supply units 120A and 120B arenot limited to supply of a processing gas of a single gas species butmay supply a plurality of gas species as processing gases. In this case,a plurality of gas supply sources may be provided with gas lines ofmultiple systems. Although it is illustrated in FIG. 10 that the gassupply unit 120A is configured to supply a gas from the side wall of theprocessing chamber 192, the gas supply unit 120A is not limited thereto.For example, a gas may be supplied from the ceiling of the processingchamber 192. In this case, e.g., a gas inlet may be formed in the centerof the plate-shaped dielectric body 194 and the gas may be supplied fromthe gas inlet.

A gas exhaust unit 130 for exhausting the internal atmosphere of theprocessing chamber 192 is connected to the bottom of the processingchamber 192 through a gas exhaust passage 132. The gas exhaust unit 130is formed with, e.g., a vacuum pump and can depressurizes the interiorof the processing chamber 192 to a predetermined pressure. In addition,radicals generated in the plasma generating space S1 move into thesubstrate processing space S2 through the partition plate 230 by adifference in pressure between the plasma generating space S1 and thesubstrate processing space S2 which is caused by the gas exhaust unit130.

A wafer loading/unloading port 134 is provided at the side wall of theprocessing chamber 192 and a gate valve 136 is provided at the waferloading/unloading port 134. For example, when the wafer W is loaded, thegate valve 136 is opened to mount the wafer W on the mounting table 110in the processing chamber 192 by a transfer mechanism (not shown) suchas a transfer arm or the like and the gate valve 136 is closed toprocess the wafer W.

On the ceiling of the processing chamber 192, the planar high frequencyantenna 140 and a shield member 160 covering the high frequency antenna140 are disposed on a top surface (outer surface) of the plate-shapeddielectric body 194. The high frequency antenna 140 in accordance withthe present embodiment is configured with, roughly, an inner antennaelement 142A disposed to correspond to the central portion of theplate-shaped dielectric body 194 and an outer antenna element 142Bdisposed to surround the periphery of the inner antenna element 142A.Each of the antenna elements 142A and 142B is formed in a spiral coilmade of a conductor such as steel, aluminum, stainless steel or thelike.

The antenna elements 142A and 142B are embedded between a plurality ofclamping bodies 144 to be one unit. Each of the clamping bodies 144 hasa columnar shape as shown in FIG. 11 and the clamping bodies 144 areradially disposed and extend from the vicinity of center of the innerantenna element 142A to the outside of the outer antenna element 142B.FIG. 11 shows an example where each of the antenna elements 142A and142B is embedded between three clamping bodies 144.

The shield member 160 includes a cylindrical inner shield wall 162Adisposed between the antenna elements 142A and 142B to surround theinner antenna element 142 a and a cylindrical outer shield wall 162Bdisposed to surround the outer antenna element 142B. Thus, the topsurface of the plate-shaped dielectric body 194 is divided into acentral portion (center zone) inside the inner shield wall 162A and aperipheral portion (peripheral zone) between the shield walls 162A and162B.

A disc-shaped inner shield plate 164A is disposed on the inner antennaelement 142A to close an opening of the inner shield wall 162A. Adoughnut-shaped outer shield plate 164B is disposed on the outer antennaelement 142B to close an opening between the shield walls 162A and 162B.

The shield member 160 is not limited to the cylindrical shape. Theshield member 160 may have other shapes such as a square column shape,preferably a shape corresponding to the shape of the processing chamber192. Here, since the processing chamber 192 has a cylindrical shape, theshield member 160 also has a cylindrical shape accordingly. If theprocessing chamber 192 has a square column shape, the shield member 160may also have a square column shape.

RF power supplies 150A and 150B are respectively connected to theantenna elements 142A and 142B. Accordingly, RF powers of the samefrequency or different frequencies can be applied to the antennaelements 142A and 142B. For example, when a specific RF power of apredetermined frequency (e.g., 40 MHz) is applied from the RF powersupply 150A to the inner antenna element 142A, a processing gasintroduced into the processing chamber 192 is excited by an inducedmagnetic field formed in the processing chamber 192 to generate adoughnut-like plasma in the central portion of the wafer W.

In addition, when a specific RF power of a predetermined frequency(e.g., 60 MHz) is applied from the RF power supply 150B to the outerantenna element 142B, a processing gas introduced into the processingchamber 192 is excited by an induced magnetic field formed in theprocessing chamber 192 to generate another doughnut-like plasma in theperipheral portion of the wafer W.

Radicals are generated from the first processing gas by the plasma. TheRF powers outputted from the RF power supplies 150A and 150B are notlimited to the above-mentioned frequencies. For example, RF powers offrequencies such as 13.56 MHz, 27 MHz, 40 MHz, 60 MHz and the like maybe applied. However, there is a need to adjust an electrical length ofeach of the antenna elements 142A and 142B depending on the RF powersoutputted from the RF power supplies 150A and 150B. In addition, heightsof the inner shield plate 164A and the outer shield plate 164B can beadjusted by actuators 168A and 168B, respectively.

The plasma processing apparatus 10 is connected with a control unit 200to control the components of the plasma processing apparatus 10. Thecontrol unit 200 is connected with an operation unit 210 including akeyboard that is used for an operator to input commands to manage theplasma processing apparatus 10, a display for visually displaying anoperation status of the plasma processing apparatus 10 and the like.

The control unit 200 is also connected with a storage unit 220 thatstores programs for realizing various processes executed in the plasmaprocessing apparatus 10 under control of the control unit 200, recipedata for executing the programs, and the like.

The storage unit 220 stores process recipes for executing processes ofthe wafer W, recipes for executing required processes, e.g., cleaning ofthe processing chamber 192 and the like. These recipes are anintegration of various parameters including control parameters forcontrol of the components of the plasma processing apparatus 10, settingparameters and the like. For example, the process recipes includeparameters such as flow rates of processing gases, an internal pressureof the processing chamber 192, frequencies and powers of RF signalsapplied to the antenna elements 142A and 142B, and the like.

These recipes may be stored in a hard disk or a semiconductor memory, ormay also be stored in a portable computer-readable storage medium suchas CD-ROM, DVD or the like and set in a predetermined location of thestorage unit 220.

The control unit 200 executes a desired process in the plasma processingapparatus 10 by reading out a desired processing recipe from the storageunit 220 in accordance with an instruction from the operation unit 210and controlling the components of the apparatus 10. In addition, therecipes can be edited according to a manipulation by an operator throughthe operation unit 210.

The above-described plasma processing apparatus 10 is used to removereaction products. FIG. 13 is a flowchart for explaining details of stepS3 shown in FIG. 3. Since the reaction products may include metalcontained in the mask 107 and the first magnetic layer 105, oxide,chloride, nitride or halide of the metal, a C or Si-containing compoundor the like, as described earlier, the reaction products cannot beremoved only with radicals or reactant gases. Therefore, the reactionproducts are pre-treated to be easily removed in step S30 (firstprocessing step) and, subsequently or simultaneously, the reactionproducts are removed in step S32 (second processing step). That is, thepre-treatment is a process of treating surfaces of the reaction productswith radicals so that the reaction products can be easily removed instep S32. In step S30, the first processing gas described above is used.The first processing gas is determined depending on the reactionproducts and a gas to remove the reaction products in step S32.

For example, when the reaction products contain metal, metal oxide, Sior SiO₂, PF₃ may be used as the second processing gas to remove thereaction products. PF₃ is coordinate bonded to metal or a compound,peeled off, evaporated and exhausted. Here, PF₃ has a property ofcoordinate bonding to neutral metal and evaporating. Therefore, in orderto efficiently remove the reaction products using PF₃, pre-treatment forreducing the metal oxide is performed. For example, H₂ is used as thefirst processing gas. H₂ is supplied into the plasma generating space S1and hydrogen radicals are generated by a plasma.

The hydrogen radicals thus generated pass through the partition plate230 to move into the substrate processing space S2 and reduce the metaloxide to metal. Subsequently or simultaneously, PF₃ is supplied to becoordinate bonded to metal, evaporated and exhausted.

In addition, e.g., when the reaction products contain metal,cyclopentadiene may be used as the second processing gas to remove thereaction products. Cyclopentadiene reacts with ionized metal(substitution reaction) to produce a compound, evaporated and exhausted.Therefore, in order to efficiently remove the reaction products usingcyclopentadiene, pre-treatment for ionizing metal is performed. Forexample, a gas which generates radicals for chloride reaction, such asCl₂, is used as the first processing gas. Cl₂ is supplied into theplasma generating space S1 and generates chloride radicals by a plasma.The chloride radicals thus generated pass through the partition plate230 to move into the substrate processing space S2 and react with metalto produce metal chloride. Subsequently or simultaneously,cyclopentadiene is supplied to react with metal chloride, evaporated andexhausted.

In addition, e.g., when the reaction products contain Si, HF may be usedas the second processing gas to remove the reaction products. HF issuitable to ash SiO₂.

Therefore, in order to efficiently remove the reaction products usingHF, pre-treatment for oxidizing Si is performed. For example, a gaswhich generates radicals for oxidation reaction, such as O₂, is used asthe first processing gas. O₂ is supplied into the plasma generatingspace Si and generates oxygen radicals by a plasma. The oxygen radicalsthus generated pass through the partition plate 230 to move into thesubstrate processing space S2 and react with Si to produce SiO₂.Subsequently or simultaneously, HF is supplied to ash SiO₂.

By repeating the above-described steps S30 and S32, the surfaces of thereaction products are treated by radicals and the reaction products areremoved. Steps S30 and S32 may be performed simultaneously.

As described above, in the plasma processing apparatus 10 in accordancewith the present embodiment, the partition plate 230 is placed withinthe processing chamber 192 to partition the internal space of theprocessing chamber 192 into the plasma generating space S1 and thesubstrate processing space S2. The partition plate 230 transmits neutralradicals while preventing transmission of ions and vacuum ultravioletrays. In addition, the first processing gas supply unit 122A suppliesthe first processing gas into the plasma generating space S1. With thisconfiguration, ions generated from the first processing gas are blockedby the partition plate 230 and only radicals generated from the firstprocessing gas are moved into the substrate processing space S2 andreact with the reaction products. In other words, only radicals requiredfor treatment of the reaction products can be taken while minimizingsubstrate damage due to ions.

In addition, the second processing gas supply unit 122A supplies thesecond processing gas into the substrate processing space S2. Therefore,the second processing gas reacts with the reaction products withoutbeing exposed to a plasma. Thus, owing to interaction between theradicals and the second reactant processing gas, it is possible toproperly remove reaction products generated when an etching target filmis etched. Since the compound coordinate bonded with the above-mentionedPF₃ or cyclopentadiene is dissociated when it is exposed to a plasma, itis difficult to efficiently peel metal off by using an electron-donatinggas under a plasma irradiation environment. However, in the plasmaprocessing apparatus 10 in accordance with the present embodiment, sincea plasma is blocked by the partition plate 230, a compound coordinatebonded with PF₃ or cyclopentadiene is not dissociated. Therefore,reaction products generated when an etching target film is etched can beproperly removed.

In addition, in the plasma processing method in accordance with thepresent embodiment, by performing the pre-treatment of step S30, onlyradicals generated from the first processing gas can be moved into thesubstrate processing space S2 to react with the reaction products. Inaddition, by performing step S32, the second processing gas can reactwith the reaction products without being exposed to a plasma. Thus,owing to interaction between the radicals and the second reactantprocessing gas, it is possible to properly remove reaction productsgenerated when a film is etched. In addition, since reactions of theradicals and the second processing gas can be consistently performed ina vacuum, it is possible to prevent new reaction products from beingformed by processing. In addition, radicals react with the reactionproducts so that the reaction products can be changed into a substancewhich is easily react with the second processing gas. Thus, due tointeraction between the radicals and the second reactant processing gas,it is possible to properly remove reaction products generated when anetching target film is etched.

In the above, the present invention has been described in detail by wayof the embodiments. However, the present invention is not limited to thedisclosed embodiments. It is to be understood that various modificationsmay be made without departing from the scope of the invention.

For example, any of the lower electrode layer 101, the pinning layer102, the second magnetic layer 103, the insulation layer 104, the firstmagnetic layer 105, the upper electrode layer 106 and the etching mask107 may have a multi-layer structure.

For example, the pre-treatment step S30 need not be necessarilyperformed. That is, the pre-treatment may not be performed depending onthe type of reaction products and/or the type of the second processinggas. For example, the reaction products are assumed to contain C ormetal such as Ti or W. In the respective cases, O₂ may be used as thesecond processing gas for removing C, Cl₂ or BCl₂ may be used as thesecond processing gas for removing Ti, and NF₃, SF₆ or CF₄ may be usedas the second processing gas for removing W. For these processes, stepS32 may be performed without performing the pre-treatment. In addition,after step S32, the subsequent steps such as recovery and observationmay be properly performed.

In addition, although it has been described in the above embodimentsthat so-called ICP (Inductively Coupled Plasma) is used as a plasmasource. However, the plasma source is not limited thereto, and a plasmasource of an electron density of an order of 10¹⁰ to 10¹², e.g., ECR(Electron Cyclotron Resonance) or a microwave, may be used. A plasmasource such as CCP (Capacitively Coupled Plasma) may be also used.

TEST EXAMPLES

The present invention will be described in more detail by way of TestExamples and a Comparative Example. However, it is to be understood thatthe present invention is not limited to the following Test Examples.

Comparative Example 1

In Comparative Example 1, a wafer W which was etched from the topsurface of the wafer W to the top surface of the insulation layer 104 asshown in FIG. 5 was observed as an initial state with an electronmicroscope. In addition, a state after supplying a HF/CH₃ gas to causereaction between the gas and reaction products was observed with theelectron microscope. FIG. 14A is a schematic view of a SEM (ScanningElectron Microscope) image before removal of the reaction products (theinitial state) and FIG. 14B is a schematic view of a SEM image aftersupplying the HF/CH₃ gas. As shown in FIGS. 14A and 14B, it wasconfirmed that bottom widths (Btm CD (Critical Dimension)) of the MRAMelement were 40 nm with no change before and after processing with theHF/CH₄ gas. That is, it was confirmed that the reaction productsgenerated by etching of a metal-containing layer could not be removedonly with the reaction gas.

Test Example 1

In Test Example 1, the wafer W in FIG. 4 as an initial state was etchedfrom the top surface of the wafer W to the top surface of the insulationlayer 104 and was observed with an electron microscope. In addition, astate after removing reaction products by the plasma processingapparatus 10 shown in FIG. 10 was observed with the electron microscope.In Test Example 1, BCl₃ and Ar were used as the first processing gas andHF was used as the second processing gas. Details are as shown below.

Space pressure: 1 Torr (133 Pa)

Power of plasma source: 300 W

BCl₃ gas: 280 sccm

Ar gas: 300 sccm

HF gas: 2000 sccm

Processing time: 180 seconds

Substrate temperature: 150° C.

FIG. 15A shows a schematic view of a cross-sectional SEM image of theinitial state of Test Example 1. FIG. 15B illustrates a schematic viewof a cross-sectional SEM image of a state of etching from the topsurface of the wafer W to the top surface of the insulation layer 104.FIG. 15C presents a schematic view of a cross-sectional SEM image of astate after removing reaction products by the plasma processingapparatus 10 shown in FIG. 10. FIG. 16A is a schematic view of a SEMimage of a state of etching from the top surface of the wafer W to thetop surface of the insulation layer 104. FIG. 16B is a schematic view ofa cross-sectional SEM image of a state after removing the reactionproducts by the plasma processing apparatus 10 shown in FIG. 10.

As shown in FIGS. 15A and 15B, it was confirmed that Btm CD was changedfrom 23.4 nm to 35.8 nm. This is because reaction products were adheredby the etching. In addition, as shown in FIGS. 15B to 16B, it wasconfirmed that reaction products were removed and Btm CD was changedfrom 35.8 nm to nm which is substantially equal to the initial value.Thus, it was confirmed that reaction products can be properly removed bythe plasma processing apparatus 10 shown in FIG. 10.

Test Example 2

In Test Example 2, the wafer W in FIG. 4 as an initial state was etchedfrom the top surface of the wafer W to the top surface of the insulationlayer 104 and was observed with an electron microscope. In addition, astate after removing reaction products with a liquid of HF (5%) and PF₃was observed with the electron microscope. Details are as shown below.

Space pressure: 20 Torr (2660 Pa)

Power of plasma source: 0 W (Non-Plasma)

PF₃ gas: 25 sccm

Processing time: 1800 seconds

Substrate temperature: 250° C.

FIG. 17A is a schematic view of a cross-sectional SEM image of theinitial state of Test Example 2. FIG. 17B is a schematic view of across-sectional SEM image of a state of etching from the top surface ofthe wafer W to the top surface of the insulation layer 104. FIG. 17C isa schematic view of a cross-sectional SEM image of a state afterremoving reaction products. FIG. 18A is a schematic view of a SEM imageof a state of etching from the top surface of the wafer W to the topsurface of the insulation layer 104. FIG. 18B is a schematic view of across-sectional SEM image of a state after removing reaction products.

As shown in FIGS. 17A and 17B, it was confirmed that Btm CD was changedfrom 23.4 nm to 30 nm. This is because reaction products were adhered bythe etching. In addition, as shown in FIGS. 17B to 18B, it was confirmedthat reaction products were removed and Btm CD was changed from 30 nm to28 nm. Thus, it was confirmed that reaction products could be properlyremoved.

Description of Reference Numerals 10 plasma processing apparatus(substrate processing apparatus) 20 substrate processing system 100 MRAMdevice 101 lower electrode layer 102 pinning layer 103 second magneticlayer 104 insulation layer 105 first magnetic layer 106 upper electrodelayer 107 etching mask 108 insulation film 110 mounting table 120A firstgas supply unit 120B second gas supply unit 192 processing chamber S1plasma generation space S2 substrate processing space W target object Zresidue

1. A substrate processing apparatus for removing reaction productsgenerated in etching an etching target layer included in a targetobject, comprising: a processing chamber defining a space; a partitionunit which is disposed in the processing chamber and partitions thespace into a plasma generating space and a substrate processing space,the partition unit being configured to suppress transmission of ions andvacuum ultraviolet rays; a plasma source configured to generate a plasmain the plasma generating space; a mounting table disposed in thesubstrate processing space for mounting the target object thereon; afirst processing gas supply unit configured to supply a first processinggas into the plasma generating space, the first processing gas to bedissociated by the plasma to generate radicals; and a second processinggas supply unit configured to supply a second processing gas into thesubstrate processing space, the second processing gas reacting with thereaction products without being exposed to the plasma.
 2. The substrateprocessing apparatus of claim 1, further comprising a gas exhaust unitwhich is provided to communicate with the substrate processing space anddepressurizes the space of the processing chamber.
 3. The substrateprocessing apparatus of claim 1, wherein the partition unit includes atleast two plate-shaped members arranged to overlap with each other seenfrom the plasma generating space toward the substrate processing space,each plate-shaped member having a plurality of through-holes penetratingtherethrough in an overlapping direction, and wherein, the through-holesof one of the at least two plate-shaped members do not overlap with thethrough-holes of the other ones of the at least two plate-shaped membersin the overlapping direction.
 4. The substrate processing apparatus ofclaim 1, wherein the radicals cause a reduction reaction, an oxidationreaction, a chloride reaction or a fluoride reaction.
 5. The substrateprocessing apparatus of claim 1, wherein the first processing gascontains hydrogen atoms, oxygen atoms, chlorine atoms or fluorine atoms.6. The substrate processing apparatus of claim 1, wherein the secondprocessing gas includes a gas whose reaction with the reaction productsis affected by a temperature of the mounting table.
 7. The substrateprocessing apparatus of claim 6, wherein the second processing gasincludes an electron-donating gas.
 8. A substrate processing method forremoving reaction products generated in etching an etching target layerincluded in a target object by using a substrate processing apparatusincluding: a processing chamber defining a space; a partition unit whichis disposed in the processing chamber and partitions the space into aplasma generating space and a substrate processing space, the partitionunit being configured to suppress transmission of ions and vacuumultraviolet rays; a plasma source configured to generate a plasma in theplasma generating space; a mounting table disposed in the substrateprocessing space for mounting the target object thereon; a firstprocessing gas supply unit configured to supply a first processing gasinto the plasma generating space, the first processing gas to bedissociated by the plasma to generate radicals; and a second processinggas supply unit configured to supply a second processing gas into thesubstrate processing space, the second processing gas reacting with thereaction products without being exposed to the plasma, the substrateprocessing method comprising: generating the radicals by supplying thefirst processing gas from the first processing gas supply unit into theplasma generating space in which a plasma is generated; moving thegenerated radicals into the substrate processing space to cause areaction with the reaction products; and supplying the second processinggas from the second processing gas supply unit into the substrateprocessing space to cause a reaction with the reaction products.
 9. Thesubstrate processing method of claim 8, wherein the generating, themoving and the supplying are performed in the same substrate processingapparatus.
 10. The substrate processing method of claim 8, wherein thegenerating and the moving are performed before or at the same time ofthe supplying.
 11. The substrate processing method of claim 8, whereinthe etching target layer includes a metal-containing layer.